A Symbolic Pole/Zero Extraction Methodology Based on Analysis of Circuit Time-Constants

This paper introduces a methodology for symbolic pole/zero extraction based on the formulation of the time-constant matrix of the circuits. This methodology incorporates approximation techniques specifically devoted to achieve an optimum trade-off between accuracy and complexity of the symbolic root expressions. The capability to efficiently handle even large circuits will be demonstrated through several practical circuits.     

控制图在土坝粘土填筑干密度控制中的应用

应用统计控制图法，选用平均值——标准差、平均值——极差控制图法，控制24^#坝粘土填筑干密度值及施工偶然异常波动，早期提出警报，以保证土坝的施工质量。     

Poly(Styrene‐Divinylbenzene) Based Media for Liquid Chromatography

The latest developments and in particular important synthetic aspects for the preparation of modern poly(styrene‐divinylbenzene) (PS‐DVB) based liquid chromatography (LC) supports are reviewed. In this context, the chemistry of particular porous and nonporous, functionalized, monolithic, coated silica and more specialized mixed organic PS‐DVB media is covered. Special consideration is given to modern approaches such as micro‐(μ)‐HPLC and coating techniques and their most important applications. Synthetic particularities relevant to the corresponding applications are outlined.     

Formation of layered structure on bismuth-borate glass surface

X-ray diffraction analysis shows that the transformation during heat treatment from amorphous to crystalline phases of bismuth-borate glass samples takes place in sequences. After a short heat treatment, 5 min at 550 °C, a layered structure with a preferred orientation of crystallites on the surface is observed. After a long heat treatment, 8 h at the same temperature, normal polycrystalline bulk samples are obtained.     

The Simulation of Impact Loads on Beam-type Structures using a Pseudo-dynamic Procedure

Abstract:  This study proposes an alternate method for the analysis of beams with solid cross-section or built as a framed structure and subjected to transverse impact loads from an external striker. The procedure used in the analysis is a combination of two essential tools using pseudo-dynamic techniques. The method reported here involves only one degree of freedom for the structure modelling and assumes an elastic contact between an external striker and the beam structure, which in reality does not happen. As only one degree of freedom is considered in the analysis, some important limitations are inherent to the method proposed here. Essentially, there is the difficulty of modelling the displacement field associated with the transient structure behaviour accurately, as a consequence of fast-rate impact loads. Another difficulty faced by the method refers to a local structure behaviour associated with contact loads. The present method can deal with large displacements in transversely loaded beams associated to a collapse mechanism having a simple geometry and defined with precision from a single parameter. This ensures reasonable accuracy in the evaluation of the strain energy absorbing capacity of transversely impacted beam structures using a single degree of freedom model in a pseudo-dynamic procedure.     

Synthesis of selenium nanoparticles in the presence of silk fibroin

This paper describes a solution-phase approach to the synthesis of selenium nanoparticles by reducing selenious acid solution with ascorbic acid in the presence of silk fibroin. The monodispersed spherical selenium colloid particles obtained were very stable in silk fibroin solution and characterized by Atomic force microscopy and X-ray techniques. The influences of temperature and ultrasonication on the morphology of selenium nanoparticles were also discussed. The experiments showed that the selenium nanoparticles with various morphologies could be obtained under different temperatures and the appropriate ultrasonication time was 60 min. This result indicated that the silk fibroin molecules intimately associated with the surface of the selenium particles and controlled the growth particles.     

Semianalytical Model for Drawdown due to Pumping a Partially Penetrating Large Diameter Well

A semianalytical model is developed for computing drawdowns in and around a partially penetrating large diameter well. The new model can take into account an unsteady pumping discharge and thus drawdowns during recovery can be computed. This model can also yield the unsteady contributions from well and aquifer storages to the pumped discharge. While developing the model, the flow from the bottom of the well is also accounted.     

综述老油田改善开发效果及提高采收率技术

中国陆上老油田已进入高含水后期开发，随着开采程度加深，地下油水关系越来越复杂，剩余油分散，给油田稳产和调整挖潜带来的难度越来越大。但目前老油田储量和产量的比例，仍占陆上总开发储量和产量的７０％以上，是生产上的主力，其潜力也最大，仍然是今后调整挖潜的主要对象。鉴于中国陆上油田绝大多数为陆相储层，构造复杂，非均质严重，原油粘度偏高，石油地质特点决定了水驱油的不均匀性及剩余油分布的复杂性，潜力就存在于这种复杂之中。根据中国陆上石油地质特点和老油田开发现状，围绕改善开发效果及提高采收率着重阐述了四个方面的配套技术：即认识油藏的配套技术，主要包括油藏动态监测技术、油藏精细描述技术、油藏数值模拟技术；完善注水开发配套技术，主要包括注水结构调整、产液结构及含水结构调整、钻取高效调整井、改造“双低”单元、配套工艺技术等；热力采油配套技术；化学驱采油配套技术。经过多年来的努力，我国陆上油田提高采收率技术有了明显进步，针对不同类型油藏潜力分布特点，采用各种有效方法及其配套技术，为挖潜增储、增产提供了很大的余地。     

Affine Dependence Classification for Communications Minimization

This paper introduces results on placement and communications minimization for systems of affine recurrence equations. We show how to classify the dependences according to the number and nature of communications they may result in. We give both communication-free conditions and conditions for an efficient use of broadcast or neighbor-to-neighbor communication primitives. Since the dependences of a problem can generally not be all communication-free, we finally introduce a heuristic to globally minimize the communications based on the classification of dependences.